i kind of wonder if i should go 5w30 or 10w30 in my new engine for cool weather driving. i've heard that generally speaking, oils with the narrowest viscosity rating have the most oil and the least polymer additives(for example 30w would be better in this sense than 10w30), but you sacrifice cold starting protection.

i've thought of running rotella 5w40 once my engine is broke in, but now considering 10w40 in the summer and 5w30 or 10w30 in the winter. anybody want to shed some light on this?

'79 sport 4x4 longbed <img src="/forums/images/graemlins/smile.gif" alt="" />
20/22R hybrid with EB's OS valves, 268c cam, offy intake, weber 32/36, thorley header, 5 speed swap, 34" LTBs, downey 3" springs, marlin hysteer, 4.88s and locked

'91 4x4 shortbed
22R-E, W56, the dd!